IR spectroscopic studies of adsorbate diffusion in porous catalysts

Transmission infrared spectroscopy has been used to study xenon diffusion through high-area porous catalysts such as alumina and silica via xenon interactions with IR-active surface species. At low temperatures, xenon condenses on the external surface of silica. As the catalyst temperature is increa...

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Bibliographic Details
Published in:Journal of physical chemistry (1952) 1989-09, Vol.93 (18), p.6758-6763
Main Authors: Ballinger, Todd H, Basu, Pam, Yates, John T
Format: Article
Language:English
Subjects:
360000 - Materials
360603 - Materials- Properties
400000 - Chemistry
400201 - Chemical & Physicochemical Properties
ADSORPTION
ALUMINATES
ALUMINIUM COMPOUNDS
CATALYSTS
CHALCOGENIDES
Chemistry
DATA
DATA ANALYSIS
DIFFUSION
Exact sciences and technology
EXPERIMENTAL DATA
General and physical chemistry
INFORMATION
INFRARED SPECTRA
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
MATERIALS SCIENCE
MEASURING INSTRUMENTS
MEASURING METHODS
MINERALS
NUMERICAL DATA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SILICA
SILICON COMPOUNDS
SILICON OXIDES
Solid-gas interface
SORPTION
SPECTRA
Surface physical chemistry
SURFACE PROPERTIES
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Summary:Transmission infrared spectroscopy has been used to study xenon diffusion through high-area porous catalysts such as alumina and silica via xenon interactions with IR-active surface species. At low temperatures, xenon condenses on the external surface of silica. As the catalyst temperature is increased and the vapor pressure of Xe increases, diffusion occurs into the pores where Xe interacts with surface hydroxyl groups, a majority of which are contained within these pores. The dynamic dipole of OH induces a dynamic dipole image in the polarizable Xe, which is opposite in sign to the OH dipole. This interaction lowers the normal frequency of OH by 28 cm{sup {minus}1}. This effect is also observed for the chemisorbed Rh{sup I}(CO){sub 2} oscillator on Al{sub 2}O{sub 3}. Evidence is presented that cooling Xe-filled pores below {approx} 153 K causes Xe condensation on itself in the pores, reducing the Xe-HO interaction as monitored spectroscopically.
ISSN:0022-3654
1541-5740
DOI:10.1021/j100355a037